We had the same problem with Morryde rubber equalizers . There is no ' tube ' between the sides of the equalizer to support grease on a wet bolt.
When I saw this issue on our 5er, Just like yours, I removed the equalizers, welded in a 1/2" pipe tube across between the sides, then drilled that out to 37/64" ( 1 64th over 9/16th) to allow wet bolts to remain stationary in the new heavy shackles, to turn in the tubing.
You need a welding shop to fix the equalizers. you can do all the rest with a jack safety blocks and 13/16 to 9/16 wrenches.
Poor design by Morryde. Either the shackles will wear or the equalizer. There is only the 2 3/16 thick shackles and the 2 1/4" plates of the morryde for wear. No tube between to bear grease or wear.
Oh, I am a welder, with a shop.
For good parts I recommend rednecktrailer.com
Just read other posts while I was writing. Carriage always made their own frames, doubled 2x6 rectangular tubing. No slide mechanism holes through the frame. no lippert I beams. The axles are Dexter, Suspension Morryde.
Please recheck your info. No Lippert frames on a Carriage.